IκBζ expression is regulated by miR-124a

IκBζ belongs to the nuclear members of the IκB protein family. Its function in regulating the activity of the transcription factor NFκB is poorly understood. Here, we demonstrate that human IκBζ is posttranscriptionally regulated by microRNA (miR)-124a. In HepG2 cells miR-124a was not endogenously expressed, but upon enforced expression dramatically inhibited the interleukin-1β-induced protein expression of IκBζ. The predicted binding site for miR-124a in the 3’UTR of the IκBζ mRNA revealed an imperfect match resulting in miR-124a-mediated suppression of IκBζ expression through translational repression. Reporter gene analyses revealed that miR-124a targets IκBζ mRNA through base pairing to the partially complementary sequence in the 3’UTR that was predicted as a binding site by in silico analysis. Furthermore, we demonstrate that the 7mer seed match is sufficient for recognition of the IκBζ mRNA. Together, our data identify IκBζ as a target of miR-124a that might be involved in the fine-tuning of NFκB-mediated gene expression.